Thermal sensing element using methanol saturated fluorocarbon elastomer as the heat responsive material

Abstract

A thermal sensing element containing a heat responsive material having a very high negative coefficient of thermal expansion. The heat responsive material contained therein is a methanol saturated copolymer of hexafluoropropylene and vinylidene fluoride. This thermal sensing element can detect minute temperature changes and can be packaged in a compact container for use in applications where space is limited.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. An improved heat responsive thermal element of the type having a first and second electrode and a volume of heat responsive material acting in combination with said electrodes to permit the flow of electricity between them when a predetermined temperature change has produced a predetermined volume change in said material, wherein the improvement comprises a heat responsive material of methanol saturated copolymer of hexafluoropropylene and vinylidene fluoride. 
     
     
       2. A thermal sensing element comprising, a tubular casing having a closed end and an open end,   a body of a heat responsive material positioned in said casing extending from the closed end toward the open end partially filling the casing, said body of material being a methanol saturated copolymer of hexafluoropropylene and vinylidene fluoride having an upper surface,   a first electrode carried by the upper surface of said body of expandable material,   a second electrode spaced from the first electrode,   means for adjusting the second electrode to a predetermined distance from said first electrode,   a seal member encasing said adjustable means and insulated electrical leads connected to said first and second electrodes positioned in said casing near the open end providing a hermetic seal such that the methanol content of said heat responsive material can not escape to the atmosphere, whereby said heat responsive material acts in combination with said electrodes to permit the flow of electricity between them when a predetermined temperature change has produced a predetermined volume change in said material.